Method and machine for forming annular bands



March 19, 1963 M. VANZO 3,082,140

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3,082,1 lil METHGD AND MACHINE FOR FGRMENG ANNULAR BANDS Marcello Vanzo,Milan, Italy, assignor to Pirelli fiocieta per Antoni, Milan, EtalyFiled Aug. 1, 1958, Ser. No. 752,587 Claims priority, application ItalyAug. 5, 1957 6 Claims. (Cl. 156-475) This invention relates to a methodof forming on a collapsible drum from one or more endless threads linedwith raw rubber or the like, annular bands even of large width, moreparticularly convenient for the resisting structures of motor vehiclewheel tires, and a machine for carrying out said method.

The improved method substantially consists in pro viding a drum, incoating the drum surface with an adhesive, rotating the drum, stretchingthe thread and laying it on the rotating drum as it is reciprocated,directly before its contact with the drum surface by means of a threadguide through which the thread is passed from one side to the other ofthe drum surface along a closed line confining a definite area situatedin a plane parallel with the drum axis, whereby the thread is laid onthe drum along a substantially zig-zag line.

Before laying it on the drum the thread is conveniently coated with araw rubber mixture, or the drum face coated with an adhesive is providedbefore laying the thread with a crude rubber layer in which the barethread is embedded.

As the thread is laid on the drum it is pressed towards the drum axis.

By effect of the rotation of the drum combined with the movement of thethread guide laying the thread on the drum face, the thread is laid onthe drum along a zig-zag line with a certain pitch which is the functionof the drum radius, peripheral speed of the drum and closed line overwhich the thread guide laying the thread is moved.

By adopting for the pitch a value wherein R is the drum radius, 11 anywhole number and s the thickness of the raw rubber lined thread, onforming the band section of the zig-zag line along which the coatedthread is laid are obtained on each successive rotation of the drum,which contact one another thereby affording a continuous band structure.

The thread guide laying thread comprises a bush through which t.e threadis passed, the drum being rotated as many times as the value s iscontained in the pitch. It is thus possible to cover the whole drumsurface by one endless thread over the desired width, the result beingan annular band composed of raw rubber thread sections parallel with oneanother, distributed over two layers at a certain angle to each other,the said annular band being free from discontinuities thanks to theadhesion of the raw rubber mix or plastic sheath enclosing the threadand forming through a special calendering step effected on laying of thethread a continuous layer within which the adjacent and intersectingthread sections merging into one another are embedded and furtherconnected together by eii'ect of the vulcanization ulti mately carriedout on the article incorporating the annular band.

According to this invention the thread may be laid in such manner thatthe abovemeutioned sections are spaced from one another, but for someuses the raw rubber should fill the interstices between the sections. Inthis case also a bare thread can be employed which is emted StatesPatent ace bedded on laying into a raw gum layer previously provided onthe drum.

Where the band is to be made up of a plurality of layers of intersectingthread sections, as above described, a layer of raw rubber or the likeshould be interposed between the layers.

It has heretofore been proposed to form the endless band by laying onethread only. When bands of considerable width are manufactured, moreparticularly bands the various longitudinal zones or which shouldexhibit dlfierent properties, two, three or a plurality of threads canbe employed, which are each laid by a special thread guide to form acorresponding longitudinal band portion.

The individual thread guides are transversely displaced by an extentcorresponding to the length of the band portion to be made therefrom,each thread guide being moved by an independent control adapted toprovide the required conditions.

For instance, when manufacturing the whole resisting structure of tirecasings, three thread guides may be employed for laying three threadsover corresponding juxtaposed longitudinal portions, the central threadguide adapted to form the cincturing structure laying its thread alongsegments at a small angle to the longitudinal plane, the lateral threadguides adapted to form the resisting carcass structure involving thesides of the tire casing laying the threads along segments forming anangle near to the said longitudinal plane. The laying pitch for theformer and the latter threads may be selected to form parallel segmentsintersecting the overlying layer, closely juxtaposed, when the threadshave been previously lined, or more or less spaced when employing eitherlined or bare threads.

interconnection of the resisting structures of the various juxtaposedportions may be eifected by means of threads extending along alongitudinal plane laid at the demarcation line between the juxtaposedportions.

Such threads laid along a longitudinal plane or approxi matelylongitudinal plane can be arranged at the margins also of each bandportion or at the margin of the band itself, when the latter comprises asingle portion being formed from one endless thread, as well as in themiddle plane of the said portion and, if desired, at intermediateregions.

The connecting threads which are adapted to improve rigidity of thestructure, such as is advantageous at the c-incturing region forpneumatic tires, can be laid before or after forming the zigzag linelayers, in special cases they may be even made at the same time as thezig-zag thread, to interlock with the latter.

On forming endless bands from two or more zig-zag threads atcorresponding juxtaposed longitudinal band portions, threads differingin properties in respect of their raw rubber lining also may be employedin order to meet requirements arising in the use of the band at thevarious longitudinal portions composing the band.

According to this invention two or more threads can be simultaneouslylaid along parallel lines throughout the width to be covered by means oftwo or more thread guides securedly fixed to one another aligned along aplane normal to the axis of the revolving drum.

Reference has been made above to a thread being laid on the drum, itbeing understood that throughout the specification the term threadshould be understood as including elementary threads coupled and twistedtogether as well as cables made from extra strong elementary threads,more particularly wires.

In the machine according to this invention the thread guide is imparteda movement which is the combination of a transverse motion and alongitudinal motion, either motion of them varying according to a lawcontrollable at will. The longitudinal movement imparted to the threadguide should be effected in the same direction of rotation of the drum,but in certain cases may be eifected in a contrary direction thereto.

The improved machine is moreover fitted with a roller which is pressedby an adjustable resilient pressure on the thread at a region coincidingwith the region at which the thread is laid on the drum or at a regionimmediately past the latter.

The roller is controlled so that its axis of rotation is in a planeperpendicular to the instantaneous laying direction.

Since the direction of the laying line is gradually varied at thereversing point, the control for varying orientation of the pressureroller should be gradually effected so as to meet with the aboverequirement for the roller axis to extend always perpendicularly to thetangent to the laying curve. The control may be eiiected for instance bymeans of a cam.

The improved machine comprises generally a support carrying the threadspools; a device for lining the thread with the raw rubber or suitableplastic; a device for stretching the thread supplied to the thread guidelaying it on the drum; means for controlling adjusting movement of thethread guide and rotation of the drum; a pressure roller acting on thethread as the latter is being laid; means for maintaining the rolleraxis constantly perpendicular to the instantaneous direction of layingof the thread.

The drum is of the collapsible type to enable removal of the continuousband when completed.

-A preferred embodiment of the improved machine comprises two crankmechanisms having an adjustable arm, one connecting rod being situatedin its middle position in a plane extending through the drum axis, theother connecting rod extending in its middle position perpendicular tothe former and being situated in a plane normal to the drum axis, theends of the said two connecting rods remote from the cranks beingarticulated in each other by means of the thread guide laying thethread.

The crank driving the connecting rod situated in the plane normal to thedrum axis is driven at twice the speed of rotation of the other crank.

Though this embodiment is preferred on account of the simplicity inmanufacture and operation, it is objectionable in that the thread cannotbe laid on the drum accurately along any desired line, more particularlyalong a symmetric curve with respect to the middle laying line, the onlypossible modifications of the form of these lines being obtainable byvarying the radius of the two cranks.

A further object of this invention is to provide a modified constructioneliminating the above drawback.

Generally the above described apparatus enables by simply adjusting thecrank radii to obtain a laying line which is near to but not coincidentwith the desired one. The modified construction corrects this differenceby subdividing the connecting rod laying in a plane extending throughthe drum axis into two sections axially displaceable relative to eachother, one of said sections or connecting rod proper being articulatedto its crank pin, the other section or connecting rod carrying thethread laying guide, the latter section being actuated by means of asuitable cam keyed to the crank pin and against which the latter sectionis biased by resilient means.

The invention further concerns a method of tracing the profile of thecam actuating the connecting red by utilising the same machine as amachine for tracing the profile of a disc keyed to the crank pin insteadof the cam, the said method consisting in tracing on the drum a lineequalling the desired laying line, but axially displaced with respect ofthe drum and parallel with itself by an extent equalling at least thesum of the maximum lateral ofiset in both directions of the desiredlaying line with respect to the line obtainable should the thread guidebe carried by the connecting rod proper, providing the latter section ofthe connecting rod or correcting rod with an extension carrying atracing indicating means arranged laterally of the disc spaced in anaxial direction with respect to the said rod by an extent equalling tooffset of the line traced on the drum, and rotating the connecting rodsand drum operatively connected thereto through small angles, the centerof the thread guide being moved on each angular displacement to theoffset line, a corresponding point being traced by means of the tracingindicating means on the side of the peripheral disc rim, the said pointsbeing interconnected by a continuous line and material being removedfrom the disc externally of the said line.

Further characteristic features of this invention will become apparentfrom the appended description referring to the accompanying drawings,wherein:

IGURE 1 is a general diagrammatic view of the machine.

FIGURE 2 shows diagrammatically a mechanism for imparting to the threadguide a movement resulting from two linear straight displacements in atransverse and parallel direction, with respect to the drum axis and alongitudinal direction, respectively, perpendicular to the drum axis,effected by the combined action of two cranks acting on slotted crankplates orthogonal to each other suitably interconnected for relativedisplacement.

FIGURES 3 to 7 show examples of thread laying lines of the drumdeveloped in a plane, corresponding to given movements of the threadguide, the trace of which, the drum being stationary, is indicatedbeside each of them (FIGURES 3a7a).

FIGURE 8 shows a device for varying the orientation of the pressureroller fitted to the mechanism controlling the thread guide shown inFIGURE 2.

FIGURE 9 relates to a device atfording the same result obtainable by thedevice shown in FIGURE 2, the masses performing the reciprocating motionand overall size being reduced.

FIGURES 10 and 11 are a front and a plan view, respectively, of themachine for forming from a single thread the endless annular band,equipped with the device shown in FIGURE 9;

FIGURES -12 and 13 are a front and plan view, respectively, of a devicefor controlling the gradual orientation of the roller pressing thethread on the drum and FIGURE 14 shows diagrammatically the succesivepositions of the pressure roller;

FIGURE 15 shows a modification of the device shown in FIGURE 9 in whichone of the two cranks effecting the movement of the thread guide isreplaced by a cam;

FIGURE 16 is an axial sectional view of a device for conferring aresilient pressure to the pressure roller acting on the thread as thelatter is being laid on the drum.

FIGURE 17 is a plan view of FIGURE 16;

FIGURE 18 is a partial sectional view corresponding to FIGURE 16,showing the device employed for releas ing the pressure roller duringoperations preparatory to formation of the endless annular band as wellas during removal of the band;

FIGURE 19 is a part development on a plane of the drum periphery or rim,on which the desired laying line, the line more nearly close theretoobtainable by the crank mechanism shown in FIGURE 9, and the laying lineofiset for purposes explained hereafter are traced, respectively,

FIGURE 20 is a front view of a detail of the machine according to amodified construction partly in section on line XXXX 0t FIGURE 21,

FIGURE 21 is a sectional view on line XXI-XXI of FIGURE 20,

FIGURE 22 shows diagrammatically a step of the cam tracing process.

Referring to the diagram shown in FIGURE 1, the improved machine forforming the endless annular band from a single thread comprises a drum 1on the annular surface of which, previously coated with an adhesive, athread guide 2 lays an endless thread 4'. Numeral 3 denotes a device formoving the thread guide 2. The thread 4 unwinds from a spool 5, travelsto an apparatus 6 lining it with a raw rubber mix, the lined threaddenoted by 4 then travelling to a stretching device diagrammaticallyindicated by a pulley having a stationary shaft 5 and an underlyingpulley with amovable shaft 9 equipped with a counterweight 7, whereuponit is fed to the thread ide 2 distributing it on the surface of the drum-1, which has been previously coated with adhesive, a pressure roller 34pressing the thread on the drum as it is being laid.

Referring to FIGURE 2, the device shown in this figure is adapted to acton the thread guide 2 laying the coated thread 4' on the drum 1 in orderto continuously move the thread guide along a closed line which is theresultant of a movement parallel with the drum axis and a movementorthogonal to the said axis.

The device comprises a rod 41 longitudinally displaceable with respectto the drum 1 in a guide 42 carried by a rod 43 perpendicular to the rod41. The rod 43 is movable in stationary guides 44. The rod 41 ends atits end opposite to that which carries the thread guide by a crossmember having a slit 45 cut therein parallel with the drum axis. The rod43 carries at one end a cross member in which a slit 49 is cutperpendicular to the slit 45 in the rod 4-1. The slit 45 has a shoe 46mounted therein, the shoe 46 being carried by a crank pin 47 rotatableabout an axis 48. The slit 49 has a shoe 50 mounted therein carried by acrank pin 51 rotatable about an axis 52. The shafts extending along theaxes 48, 52, respectively, are rotated, the rate of speed of the shaft43 being twice the rate of speed of the shaft 52.

With the device of the type disclosed above the thread guides 2 mayfollow closed lines confining a definite surface. Examples of suchclosed lines are shown in FIG- URES 3a and 7a, beside each of which theline along which the thread is laid on the drum is shown developed in aplane.

It will be seen that the closed lines obtained by a device of thisconstruction are all in the form of an 8. The length of each 8-shapedfigure is twice the eccentricity of the pivot 51, its width being twicethe eccentricity of the pivot 47. The adjustment of the bands width istherefore obtained by varying the eccentricity of the pivot 51, the formof the various sections of the laying line on the drum, moreparticularly the connecting portions between the various sections on theband edges is varied by adjusting the eccentricity of the pivot 47. Itwill be seen that the smaller the eccentricity of the pivot 47 (FIGURES3 and 3a) the larger is the radius of the connections between thesections of the laying line, while the greater the eccentricity (FIGURES4, 4a and 5, 5a) the sharper are the connections, and still greatereccentricities result in loops. By reversing the rotation of the shaft48 and maintaining the eccentricity of the pivot 47 similar as adoptedin FIG- URE 4a, connections result which exhibit a substantiallyrectilinear section (FIGURE 7).

The device shown in FIGURE 2 affords transverse rates of speeds whichconstantly follow those determined by the eccentrics and may thereforebe varied according to fixed laws only, unless the angular rate of speedof the eccentrics on revolution is varied or the eccentrics are replacedby cams, or the rate of speed of the drum is varied during revolutionthereof.

In order to operate the roller pressing the thread the device shown inFIGURE 8 may be employed, which comprises a cam 53 keyed to a pivot 51'coaxial and fixedly secured to the crank pin 51 rotating about the axis52.

A roller 54 is pressed against a profile of the cam 53 by a bell cranklever 55, 55' capable of oscillating about the pivot 56.

The arm 55' of the bell crank lever mentioned above has anchored theretoone end of a flexible transmission cable 57, the sheath of which isdenoted by 58. The

other end of the cable 57 is provided with a member 62 for adjustableengagement into the slit 63 of a bell crank lever 59, 59' keyed to thepivot 31 which carries the roller'34 pressing the thread being laid,this pin 31 (which is made hollow for the thread to extend therethroughand be guided thereby) being rotatable in a suitable bush on the rod4 1. The arm 59 of the bell crank lever is subjected to the action of aspring 61 tending to oscillate it and holding the cable 57 stretched atthe same time causing the roller 54 to contact the cam 53.

Referring to FIGURE 9 the device diagrammatically shown in this figureis adapted to confer to the thread guide a combined motion similar tothe motion transmitted by the slotted cranks 45 and 49 of the deviceshown in FIGURES 2 and 8, while advantageously reducing the overall sizeand reciprocating masses.

In this device the shafts 52 and 48 have keyed thereto crank discs 67,68, respectively. The disc 67 is formed with a radial groove 69 whichengages and holds at the desired distance from the axis of rotation thecrank pin 51 articulated to the connecting rod 64. Similarly, the radialgroove 70 in the crank plate 63 adjustably engages and retains the crankpin 47 articulated to the connecting rod 65-. The crank disc as isrotated as mentioned above at an angular speed which istwice the rate ofspeed of the crank plate 67. The two connecting rods 64, 65 arearticulated to each other at 66, the hollow pivot for the pressureroller for the thread being laid extending through the articulationpivot for the connecting rods. The axial bore in the pivot for thepressure roller has the thread extending therethrough and serves asthread guide, all as hereafter described in detail with reference toFIGURES 16, 17 and 18.

The device shown in FIGURE 2 yields a laying line made up of rectilinearsections merging into one another, while the device shown in FIGURE 9cannot yield accurately rectilinear sections, the sections beingapproximately rectilinear enough for certain uses as reinforcements fortires.

Referring to FIGURES l0 and 11, the machine shown in these figurescarries the mechanism operating the thread guide 2 shown in FIGURE 9,comprising two crank plates 67, 68, the latter plate rotating at twicethe angular speed of the former, the plates having radial groovestherein for securing the pivot for the crank pin 51, 47 respectively.

Motion is imparted by one motor 71 which rotate-s through a belt 72 ashaft 73 having keyed thereto a pulley 74 over which the belt travels.The shaft 73 has keyed thereto two toothed Wheels 75, 77. The toothedwheel 75 rotates, through a set of gears 76, the shaft 52 having keyedthereto the crank plate 67, and rotates, through the transmission 74'and corresponding toothed wheel pair at twice the angular speed, theshaft 48 having keyed thereto the crank plate 68.

The toothed wheel 77 rotates through a set of gears 78 a shaft 79 whichrotates through a suitable bevel gearing the drum 1. By exchanging thetoothed wheels in both gearings the ratio of the rotational speed of thedrum 1 to the translational speed of the thread guide may be varied,thereby varying the number of windings and the angular displacement ofthe laying path on successive revolutions.

A variable speed transmission can be used instead of the above mentionedgearings, the transmission being interposed between the drum rotatingmechanism and mechanism for translating the thread guide. The purposemay be alternatively served by a variable speed transmission determiningthe angular displacement of the laying path on the successive revolutionof the drum, while the interchangeable toothed wheel gearing may beemployed for determining the pitch of zig-zag laying of the thread only.

The machine may be provided with an automatic stop device known per sewhich is released as a predetermined number of windings has been laid.

FIGURES 12 and 13 show the device for gradually varying orientation ofthe pressure roller 34 fitted to the device shown in the precedingfigures, more particularly to the crank plate 67. The device comprises acam 53' keyed to a pivot 51 on the axial extension of the crank pin 51.The profile of the cam 53' has a roller 54 rolling thereon, the roller54 being carried by a bell crank lever 55, S capable of oscillatingabout a pivot. The arm 55' of the bell crank lever is formed with alongitudinal slit 81 adjustably engaging in a radial direction the pivot80 of the connecting rod 82 articulated at its other end to the end ofthe lever 83 keyed to the pivot carrying the pressure roller '34.Rotation of the crank plate 67 therefore orientates the roller 34 asdesired by means of the cam 53'.

The successive positions of the rollers 34 are shown in FIGURE 14.

Referring to FIGURE 15, in the device shown therein, the crank plate 67actuating the connecting rod 64 is maintained, the other crank plate 68being replaced on the shaft 48 by a cam 92 with the profile of which theroller 91 is caused to contact, the roller 91 being carried by a strap90 mounted on the end of the rod 65 connected at its other end at 66with the connecting rod 64 at the pivot of the pressure roller. Thestrap 90 is articulated at 93 to a lever 94 articulated in turn at 95 toa fixed point. In the example shown the cam 92 comprises two symmetricalparts, so that the number of revolutions of the shaft 48 equals thenumber of revolutions of the shaft 52 carrying the plate 67.

Referring to FIGURES 16, 17 and 18 which show the pressure roller 34pressing the thread being laid on the drum 1, the numeral 96 denotes acoiled spring, conferring the necessary resilient pressure to the roller'34 and mounted for this purpose in an annular chamber longitudinallyformed between the pivot 31 and pivot 66 articulating the levers 64 and65 to each other, the said levers controlling movement of the threadguide 2 formed by the axial bore in the pivot 31. The forked end 33 ofthe pivot 31 supports the shaft 34' on which the pressure roller 34rotates.

In order to release the pressure roller 34 and lift it from the surfaceof the drum 1 any time this is required, a handle-shaped disc 97 isprovided, having holes 98 bored therethrough and securedly fixed to theend of the hollow pivot 31. The ends of the pivot 66 articulatingtogether the levers 64 and 65 have secured thereto two rods 99, theposition of which is such as to engage with holes 98 when the latter arecaused to coincide with the said rods. The engagement position shown inFIGURE 16 holds the roller 34 in the operative position. In order torelease it from this position and set free the surface of the drum 1,the disc 97 is lifted and carries along the pivot 31 to which issecurely fixed, hence the pressure roller 34. In order to maintain thepressure roller in the lifted position, it will be sufiicient toslightly angularly displace the disc 97 to move the rods 99 out of thealignment holes 98, such as to the position indicated by 99' in FIGURE20.

The spring 96 holds the disc 97 pressed against the heads of the rods99, so that the pressure roller 34 remains in its lifted inoperativeposition until the disc 97 is imparted an equal contrary angularmovement bringing the rods 99 into register with the holes 98.

The previously described embodiments permit of laying the thread on thedrum rim along a wide variety of laying lines but do not affordparticularly desirable laying lines. According to a further aspect ofthis invention shown with reference to FIGURES 19 to 21 the thread canbe laid on the drum along any desired laying line.

In FIGURE 19, 1 denotes the drum surface on which a broken line B showsthe desired thread laying line, and a full line A shows the laying linewhich could be obtained by the machine according to the above describedconstruction. The modification improves the abovernen- 5 tionedconstruction to permit of laying the thread along the line B.

To this end the connecting rod 64 lying in the plane extending throughthe drum axis is subdivided into two tubular portions telescopicallysliding within each other, the former portion 101, acting as aconnecting rod proper and being articulated to the crank pin 51 througha sleeve 102, the latter portion or connecting rod denoted by 64carrying the thread guide 2 for laying the thread. The displacement ofthe connecting rod with respect to the connecting rod proper is obtainedby means of a cam 103 keyed to the crank pin 51. The connecting rod hassecured thereto a support 104 for a roller 106 rotatable on a pivot .105and rolling in contact with a cam 103. The connecting rod is biasedtowards the cam 103, so that the roller 106 rolls in contact therewith,by a helical spring 107 acting at one end against the fiange 108provided within the connecting rod and bearing at its other end on aflanged sleeve 109 screwed on a rod 110, the latter being secured inturn to a cylindrical extension 111 on the sleeve 102, the connectingrod proper being fitted on said extension.

The crank pin 51, mounted in the same manner as in the previouslydescribed construction for radial displacement within a slit or groovein the crankplate 67 has keyed thereto a cam 53 controlling through abell crank arm and a rod (not shown on the drawing for the sake ofclearness, but arranged as shown in FIGURES 12 and 14), orientation ofthe roller adapted to press the thread against the drum as it is beinglaid.

It will be obvious that through a suitable construction of the cam 103,any predetermined laying line for the thread on the rotary drum can beobtained. For instance, the construction shown on the drawing affords alaying line as shown at B in FIGURE 19, by previously arranging thecrank pins in a suitable position for tracing the line A closelyapproaching the desired line B.

The invention further concerns a method of tracing the profile of thecam v103 actuating the connecting rod 64 by utilizing the same machineas a device for tracing the profile on a disc keyed to the crank pininstead of the cam.

As shown in FIGURE 22, in order to carry out this method a disc 103 iskeyed to the crank pin 51, the disc 103' exceeding or equalling inradius the maximum radius of the earn 103. The support 104 for theroller 106 is fixed to a support 112 carrying a nut 113 into which ascrew 114 having a milled head is screwed.

The screw 114 abuts an abutment 115 welded to the arm 116 supporting thepivot 117 to which the crank arm is pivoted, this bell crank armcontrolling orientation of the roller pressing the thread against thedrum. It will be seen that, by rotating the screw 114 the rod 64 isaxially displaced, thereby removing the roller 106 from the periphery ofthe disc 103'. An extension 118 is welded to the support 104, the saidextension being arranged laterally of the disc and provided with a hole119 for the purposes to be described hereafter.

The process for tracing the cam 103 is as follows: A line C is drawn onthe drum 1 (FIGURE 19), said line being made up, for instance, of thedesired laying line B axially displaced with respect to the drum andparallel with itself by an extent 0 equalling at least the sum of themaximum lateral offsets in both direction a b, (equalling each other inthe example shown on the drawings) of the desired laying line B withrespect to the line A obtainable where the connecting rod would bedirectly pivoted to the crank pin; the spacing of the axis of the hole119 and periphery of the roller 106 is selected to equal the abovedefined length c. The screw .114 having a milled head is subsequentlyacted upon to move the centre of the thread guide to any point on thecurve C and a point is drawn by means of a tracing pin, fitted throughthe hole 119, on the front face of the disc 103; the driving shaft ofthe machine is then sequentially rotated through small angles, furtherpoints being drawn still in the manner 9 described above on the face ofthe disc 103; it will be obvious that upon removing material 103a fromthe disc externally of the line C the cam 103 is accurately obtained.

The cam tracing method is very quick and simple. Of course, everydesired laying line requires a special cam.

The cams can be each stored with a pair of tools adapted to accuratelydefine the eccentricity of both cranks in order to obtain a determinedlaying line.

It will be understood that, the principle of the invention being leftunaltered embodiments of the method and constructional details of themachine can be widely varied from the non limiting example described andillustrated without departing from the scope of this invention.

What I claim is:

1. A method of forming annular bands from at least one endless thread ona collapsible drum, said annular bands being suitable for reinforcementof tire casings for motor vehicle wheels, comprising the steps of providing a drum, coating the periphery of said drum with an adhesive,rotating the drum, stretching the thread and laying it on the rotatingdrum while the thread, immediately before its contact with the drumperiphery, is subjected to a first reciprocation between the sides ofsaid drum and is simultaneously subjected to a second reciprocation in adirection perpendicular to the direction of said first reciprocation,the direction of said second reciprocation and the rate of bothreoiprocations being so selected that said thread follows, immediatelybefore its contact with the drum periphery, a closed path substantiallyof figure S-Shape' lying in a plane parallel with the drum axis.

2. A method as claimed in claim 1, wherein the movement of the threadalong said path is such that the dis- 10 placement of the thread nearthe drum sides takes place in the same direction as the movement of thedrum periphery.

3. A method as claimed in claim 1, wherein the rate of feed of thethread is varied upon laying the latter on the drum periphery.

4. A method as claimed in claim 1, wherein, during the laying of thethread on the drum periphery, the speed of rotation of the drum. isvaried.

5. A method as claimed in claim 1, wherein at least two threads aresimultaneously laid on the drum periphery along lines parallel with eachother.

6. A method as claimed in claim 1, wherein at least two threads aresimultaneously laid on the drum periphery along lines independent ofeach other.

References Cited in the file of this patent UNITED STATES PATENTS1,213,600 Dunkerley Jan. 23, 1917 2,264,424 Winslow Dec. 2, 19412,248,832 Taylor July 8, 1941 2,411,659 Manning Nov. 26, 1946 2,574,221Modigliani Nov. 6, 1951 2,609,320 Modigliani Sept. 2, 1952 2,614,058Francis Oct. .14, 1952 2,692,005 DeCloud Oct. 19, 1954 2,758,037 CahillAug. 7, 1956 2,760,550 Kimes Aug. 28, 1956 2,849,049 Hanson Aug. 26,1958 2,874,456 Weidel Feb. 24, 1959 2,906,314 Trevaskis Sept. 29, 19592,920,384 Fasoli Jan. 12, 1960 3,002,874 Lowe Oct. 3, 1961

1. A METHOD OF FORMING ANNULAR BANDS FROM AT LEAST ONE ENDLESS THREAD ONA COLLAPSIBLE DRUM, SAID ANNULAR BANDS BEING SUITABLE FOR REINFORCEMENTOF TIRE CASINGS FOR MOTOR VEHICLE WHEELS, COMPRISING THE STEPS OFPROVIDING A DRUM, COATING THE PERIPHERY OF SAID DRUM WITH AN ADHESIVE,ROTATING THE DRUM, STRECTCHING THE THREAD AND LAYING IT ON THE ROTATINGDRUM WHILE THE THREAD, IMMEDIATELY BEFORE ITS CONTACT WITH THE DRUMPERIPHERY, IS SUBJECTED TO A FIRST RECIPROCATION BETWEEN THE SIDES OFSAID DRUM AND IS SIMULTANEOUSLY SUBJECTED TO A SECOND RECIPROCATION IN ADIRECTION PREPENDICULAR TO THE DIRECTION